Authors: Mascha EJ et al., Anesthesiology 2015 Jul 123:79
Intraoperative hypotension was much more important than intraoperative hypertension or BP variability.
Adverse effects of severe hypotension during surgery are quite clear. But what about intraoperative hypertension or marked variability of blood pressure (BP) during surgery? Two studies shed light on this question.
A study from six U.S. veterans’ hospitals included data from 18,756 noncardiac surgeries, for which 30-day mortality was 1.8%. As expected, progressively severe intraoperative hypotension was associated with increasing 30-day mortality; the longer the duration of hypotension, the greater the mortality risk. In contrast, progressively higher intraoperative blood pressures were not associated with increasing mortality. These analyses were adjusted for preoperative patient characteristics that confer perioperative risk.
In a study from Cleveland Clinic, researchers examined the effect of intraoperative BP variability during 104,400 noncardiac surgeries lasting at least 1 hour; 30-day mortality was 1.3%. In analyses adjusted for potentially confounding risk variables, lower BP variability was associated with slightly higher mortality. This outcome was independent of patients’ time-weighted-average mean arterial pressure.
The first study corroborated the expected adverse effect of intraoperative hypotension but also showed that intraoperative hypertension was not associated with excess mortality. In the second study, lesser — not greater — BP variability was associated with excess mortality. The authors speculate that the latter finding could reflect undesirable effects of autonomic dysfunction. Although these associations are not necessarily causal, they imply that intraoperative hypertension and BP variability deserve much less attention than intraoperative hypotension.